Internet Engineering Task Force Q. Zhao Internet-Draft Huawei Technology Intended status: Standards Track L. Fang Expires: September 12, 2012 C. Zhou Cisco Systems L. Li China Mobile N. So Verizon Business K. Kamran Cisco Systems March 11, 2012 LDP Extensions for Multi Topology Routing draft-ietf-mpls-ldp-multi-topology-03.txt Abstract Multi-Topology (MT) routing is supported in IP networks with the use of MT aware IGP protocols. In order to provide MT routing within Multiprotocol Label Switching (MPLS) Label Distribution Protocol (LDP) networks new extensions are required. This document describes the LDP protocol extensions required to support MT routing in an MPLS environment. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 12, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. Zhao, et al. Expires September 12, 2012 [Page 1] Internet-Draft LDP Multi Topology Extensions March 2012 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Zhao, et al. Expires September 12, 2012 [Page 2] Internet-Draft LDP Multi Topology Extensions March 2012 Table of Contents 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Signaling Extensions . . . . . . . . . . . . . . . . . . . . . 5 4.1. Topology-Scoped FEC . . . . . . . . . . . . . . . . . . . 5 4.2. New Address Families: MT IP . . . . . . . . . . . . . . . 5 4.3. LDP FEC Elements with MT IP AF . . . . . . . . . . . . . . 7 4.4. IGP MT-ID Mapping and Translation . . . . . . . . . . . . 8 4.5. LDP MT Capability Advertisement . . . . . . . . . . . . . 8 4.6. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 9 4.7. LDP Sessions . . . . . . . . . . . . . . . . . . . . . . . 10 4.8. Reserved MT ID Values . . . . . . . . . . . . . . . . . . 11 5. MT Applicability on FEC-based features . . . . . . . . . . . . 11 5.1. Typed Wildcard FEC Element . . . . . . . . . . . . . . . . 11 5.2. End-of-LIB . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1. MT Error Notifications . . . . . . . . . . . . . . . . . . 12 6.2. MT Advisory Notifications . . . . . . . . . . . . . . . . 12 7. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 12 8. MPLS Forwarding in MT . . . . . . . . . . . . . . . . . . . . 13 9. Security Consideration . . . . . . . . . . . . . . . . . . . . 13 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 14 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.1. Normative References . . . . . . . . . . . . . . . . . . . 14 12.2. Informative References . . . . . . . . . . . . . . . . . . 15 Appendix A. Appendix . . . . . . . . . . . . . . . . . . . . . . 15 A.1. Application Scenarios . . . . . . . . . . . . . . . . . . 15 A.1.1. Simplified Data-plane . . . . . . . . . . . . . . . . 15 A.1.2. Using MT for P2P Protection . . . . . . . . . . . . . 15 A.1.3. Using MT for mLDP Protection . . . . . . . . . . . . . 16 A.1.4. Service Separation . . . . . . . . . . . . . . . . . . 16 A.1.5. An Alternative inter-AS VPN Solution . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Zhao, et al. Expires September 12, 2012 [Page 3] Internet-Draft LDP Multi Topology Extensions March 2012 1. Terminology This document uses MPLS terminology defined in [RFC5036]. Additional terms are defined below: o MT-ID: A 16 bit value used to represent the Multi-Topology ID. o Default MT Topology: A topology that is built using the MT-ID default value of 0. o MT Topology: A topology that is built using the corresponding MT-ID. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 2. Introduction It would be advantageous for Communications Service Providers (CSP) to support Multiple Topologies (MT) within MPLS environments (MPLS-MT). Beneficial MPLS-MT deployment scenarios include: o A CSP may want to assign varying QoS profiles to traffic, based on a specific MT. o Separate routing and MPLS domains may be used to isolated multicast and IPv6 islands within the backbone network. o Specific IP address space could be routed across an MT based on security or operational isolation requirements. o Low latency links could be assigned to an MT for delay sensitive traffic. o Management traffic could be separated from customer traffic using multiple MTs, where the management traffic MT does not use links that carries customer traffic. 3. Requirements The following specific requirements and objectives have been defined in order to provide the functionality described in Section 2 (Introduction), and facilitate CSP configuration and operation: Zhao, et al. Expires September 12, 2012 [Page 4] Internet-Draft LDP Multi Topology Extensions March 2012 o Minimise configuration and operation complexity of MPLS-MT across the network. o The MPLS-MT solution SHOULD NOT require data-plane modification. o The MPLS-MT solution MUST support multiple topologies. Allowing a an MPLS LSP to be established across a specific, or set of, multiple topologies. o Control and filtering of LSPs using explicitly including or excluding multiple topologies MUST be supported. o The MPLS-MT solution MUST be capable of supporting QoS mechanisms. o The MPLS-MT solution MUST be backwards compatibility with existing LDP message authenticity and integrity techniques, and loop detection. o Deployment of MPLS-MT within existing MPLS networks should be possible, with nodes not capable of MPLS-MT being unaffected. 4. Signaling Extensions 4.1. Topology-Scoped FEC LDP assigns and binds a label to a FEC, where a FEC is a list of one of more FEC elements. To setup LSPs for unicast IP routing paths, LDP assigns local labels for IP prefixes, and advertises these labels to its peers so that an LSP is setup along the routing path. To setup MT LSPs for IP prefixes under a given topology scope, the LDP "prefix-related" FEC element must be extended to include topology info. This infers that MT-ID becomes an attribute of Prefix-related FEC element, and all FEC-Label binding operations are performed under the context of given topology (MT-ID). The following Subsection (4.2 New Address Families: MT IP) defines the extension required to bind "prefix-related" FEC to a topology. 4.2. New Address Families: MT IP The LDP base specification [RFC5036] (Section 4.1) defines the "Prefix" FEC Element as follows: Zhao, et al. Expires September 12, 2012 [Page 5] Internet-Draft LDP Multi Topology Extensions March 2012 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix (2) | Address Family | PreLen | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Prefix FEC Element Format [RFC5036] Where "Prefix" encoding is as defined for given "Address Family", and whose length (in bits) is specified by the "PreLen" field. To extend IP address families for MT, two new Address Families named "MT IP" and "MT IPv6" are used to specify IPv4 and IPv6 prefixes within a topology scope. The format of data associated with these new Address Family is: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | MT-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: MT IP Address Family Format Where "IP Address" is an IPv4 and IPv6 address/prefix for "MT IP" and "MT IPv6" AF respectively, and the field "MT-ID" corresponds to 16- bit Topology ID for given address. Where 16-bit "MT-ID" field defines the Topology ID, and the definition and usage of the rest fields in the FEC Elements are same as defined for IP/IPv6 AF. The value of MT-ID 0 corresponds to default topology and MUST be ignored on receipt so as to not cause any conflict/confusion with existing non-MT procedures. The proposed FEC Elements with "MT IP" Address Family can be used in any LDP message and procedures that currently specify and allow the use of FEC Elements with IP/IPv6 Address Family. [Editors Note - RFC[5036] doesn't specify the handling of unknown Address Family. After we have introduced the two new address family here, RFC[5036] need to be updated to add the handling procedure for Zhao, et al. Expires September 12, 2012 [Page 6] Internet-Draft LDP Multi Topology Extensions March 2012 the unknown address families. 4.3. LDP FEC Elements with MT IP AF When introducing the new Address Family, it will make the extension to all the prefix-related FEC Elements by nature. This section specifies the format extensions of the existing LDP FEC Elements. The "Address Family" of these FEC elements will be set to "MT IP" or "MT IPv6". The MT Prefix FEC element will be encoded as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix (2) | Address Family (MT IP/MT IPv6)| PreLen | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | MT-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: MT Prefix FEC Element Format Similarly, the MT mLDP FEC elements will be encoded as follows, where the mLDP FEC Type can be P2MP(6), MP2MP-up(7), and MP2MP-down(8): 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | mLDP FEC Type | Address Family (MT IP/MT IPv6)| Address Length| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Root Node Address ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | MT-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Opaque Length | Opaque Value ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + ~ ~ | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: MT mLDP FEC Element Format Zhao, et al. Expires September 12, 2012 [Page 7] Internet-Draft LDP Multi Topology Extensions March 2012 And the MT Typed Wildcard FEC element encoding is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Typed Wcard (5)| FEC Type | Len = 6 | AF = MT IP ..| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |... or MT IPv6 | MT ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: MT Typed Wildcard FEC Element 4.4. IGP MT-ID Mapping and Translation The non-reserved non-special IGP MT-ID values can be used/carried in LDP as-is and need no translation. However, there is a need for translating reserved/special IGP MT-ID values to corresponding LDP MT-IDs. The corresponding special/reserved LDP MT-ID values are defined in later section 10. 4.5. LDP MT Capability Advertisement We specify a new LDP capability, named "Multi-Topology (MT)", which is defined in accordance with LDP Capability definition guidelines [RFC5561]. The LDP "MT" capability can be advertised by an LDP speaker to its peers either during the LDP session initialization or after the LDP session is setup to announce LSR capability to support MTR for the given IP address family. The "MT" capability is specified using "Multi-Topology Capability" TLV. The "Multi-Topology Capability" TLV format is in accordance with LDP capability guidelines as defined in [RFC5561]. To be able to specify IP address family, the capability specific data (i.e. "Capability Data" field of Capability TLV) is populated using "Typed Wildcard FEC Element" as defined in [RFC5918]. The format of "Multi-Topology Capability" TLV is as follows: Zhao, et al. Expires September 12, 2012 [Page 8] Internet-Draft LDP Multi Topology Extensions March 2012 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| Multi-Topology Cap.(IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |S| Reserved | | +-+-+-+-+-+-+-+-+ | ~ Typed Wildcard FEC element(s) ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Multi-Topology Capability TLV Format Where: o U- and F-bits: MUST be 1 and 0, respectively, as per Section 3 of LDP Capabilities [RFC5561]. o Multi-Topology Capability: Capability TLV type (IANA assigned) o S-bit: MUST be 1 if used in LDP "Initialization" message. MAY be set to 0 or 1 in dynamic "Capability" message to advertise or withdraw the capability respectively. o Typed Wildcard FEC element(s): One or more elements specified as the "Capability data". o Length: The length (in octets) of TLV. The encoding of Typed Wcard FEC element, as defined in [RFC5561], is defined in the section 4.3 of this document. 4.6. Procedures To announce its MT capability for given IP address family, given LDP FEC type, and given Multi Topology, an LDP speaker MAY send "MT Capability" including the exact Typed Wildcard FEC element with corresponding "Address Family" field (i.e. set to "MT IP" for IPv4 and set to "MT IPv6" for IPv6 address family), corresponding "FEC Type" field (i.e. set to "P2P", "P2MP", "MP2MP"), and corresponding "MT-ID". To announce its MT capability for both IPv4 and IPv6 address family, or for multiple FEC types, or for multiple Multi Topologies, an LDP speaker MAY send "MT Capability" with one or more MT Typed FEC elements in it. o The capability for supporting multi-topology in LDP can be advertised during LDP session initialization stage by including the LDP MT capability TLV in LDP Initialization message. After Zhao, et al. Expires September 12, 2012 [Page 9] Internet-Draft LDP Multi Topology Extensions March 2012 LDP session is established, the MT capability can also be advertised or withdrawn using Capability message (only if "Dynamic Announcement" capability [RFC5561] has already been successfully negotiated). o If an LSR has not advertised MT capability, its peer must not send messages that include MT identifier to this LSR. o If an LSR receives a Label Mapping message with MT parameter from downstream LSR-D and its upstream LSR-U has not advertised MT capability, an LSP for the MT will not be established. o We propose to add a new notification event to signal the upstream that the downstream is not capable. o If an LSR is changed from non-MT capable to MT capable, it sets the S bit in MT capability TLV and advertises via the Capability message. The existing LSP is treated as LSP for default MT (ID 0). o If an LSR is changed from LDP-MT capable to non-MT capable, it may initiate withdraw of all label mapping for existing LSPs of all non-default MTs. Then it clears the S bit in MT capability TLV and advertises via the Capability message. o If an LSR is changed from IGP-MT capable to non-MT capable, it may wait until the routes update to withdraw FEC and release the label mapping for existing LSPs of specific MT. o There will be case where IGP is MT capable but MPLS is not and the handling procedure for this case is TBD. 4.7. LDP Sessions Depending on the number of label spaces supported, if a single global label space is supported, there will be one session supported for each pair of peer, even there are multiple topologies supported between these two peers. If there are different label spaces supported for different topologies, which means that label spaces overlap with each other for different MTs, then it is suggested to establish multiple sessions for multiple topologies between these two peers. In this case, multiple LSR-IDs need to be allocated beforehand so that each multiple topology can have its own label space ID. [Editors Note - This section requires further discussion] Zhao, et al. Expires September 12, 2012 [Page 10] Internet-Draft LDP Multi Topology Extensions March 2012 4.8. Reserved MT ID Values Certain MT topologies are assigned to serve pre-determined purposes: Default-MT: Default topology. This corresponds to OSPF default IPv4 and IPv6, as well as ISIS default IPv4. A value of 0 is proposed. ISIS IPv6 MT: ISIS default MT-ID for IPv6. Wildcard-MT: This corresponds to All-Topologies. A value of 65535 (0xffff) is proposed. We propose a new IANA registry "LDP Multi-Topology ID Name Space" under IANA "LDP Parameter" namespace to keep LDP MT-ID reserved value. If an LSR receives a FEC element with an "MT-ID" value that is "Reserved" for future use (and not IANA allocated yet), the LSR must abort the processing of the FEC element, and SHOULD send a notification message with status code "Invalid MT-ID" to the sender. [Editors Note - This section requires further discussion]. 5. MT Applicability on FEC-based features 5.1. Typed Wildcard FEC Element [RFC5918] extends base LDP and defines Typed Wildcard FEC Element framework. Typed Wildcard FEC element can be used in any LDP message to specify a wildcard operation/action for given type of FEC. The MT extensions proposed in document do not require any extension in procedures for Typed Wildcard FEC element, and these procedures apply as-is to MT wildcarding. The MT extensions, though, allow use of "MT IP" or "MT IPv6" in the Address Family field of the Typed Wildcard FEC element in order to use wildcard operations in the context of a given topology. The use of MT-scoped address family also allows us to specify MT-ID in these operations. The proposed format in section 4.3 allows an LSR to perform wildcard FEC operations under the scope of a topology. If an LSR wishes to perform wildcard operation that applies to all topologies, it can use "Wildcard Topology" MT-ID as defined in section 4.8. For instance, upon local un-configuration of topology "x", an LSR may send wildcard label withdraw with MT-ID "x" to withdraw all its labels from peer that were advertised under the scope of topology "x". On the other hand, upon some global configuration change, an LSR may send wildcard Zhao, et al. Expires September 12, 2012 [Page 11] Internet-Draft LDP Multi Topology Extensions March 2012 label withdraw with MT-ID set to "Wildcard Topology" to withdraw all its labels under all topologies from the peer. 5.2. End-of-LIB [RFC5919] specifies extensions and procedures for an LDP speaker to signal its convergence for given FEC type towards a peer. The procedures defined in [RFC5919] apply as-is to MT FEC element. This means that an LDP speaker MAY signal its IP convergence using Typed Wildcard FEC element, and its MT IP convergence per topology using MT Typed Wildcard FEC element (as defined in earlier section). 6. Error Handling The extensions defined in this document utilise the existing LDP error handling defined in [RFC5036]. Errors and events are signaled to MPLS-MT peers using LDP notification messages. There are two kinds of MPLS-MT notification messages: 1. Error Notifications. These are used to signal fatal errors. If an LSR receives an error notification from a peer for an MPLS-MT session, it terminates the LDP session by closing the TCP transport connection for the session and discarding all MT-ID label mappings learned via the session. 2. Advisory Notifications. These are used to pass an LSR information about the MT-ID LDP session and the status of some previous message received from the peer. 6.1. MT Error Notifications Multi-Topology Capability not supported. Invalid Topology ID 6.2. MT Advisory Notifications Unknown Address Family ("MT IP" and "MT IPv6") 7. Backwards Compatibility The MPLS-MT solution is backwards compatible with existing LDP enhancements defined in [RFC5036], including message authenticity, integrity of message, and topology loop detection. Zhao, et al. Expires September 12, 2012 [Page 12] Internet-Draft LDP Multi Topology Extensions March 2012 8. MPLS Forwarding in MT Although forwarding is out of the scope of this draft, we include some forwarding consideration for informational purpose here. The specified signaling mechanisms allow all the topologies to share the platform-specific label space; this is the feature that allows the existing data plane techniques to be used; and the specified signaling mechanisms do not provide any way for the data plane to associate a given packet with a context-specific label space. 9. Security Consideration No specific security issues with the proposed solutions are known. The proposed extension in this document does not introduce any new security considerations beyond that already apply to the base LDP specification [RFC5036] and [RFC5920]. 10. IANA Considerations The document introduces following new protocol elements that require IANA consideration and assignments: o New LDP Capability TLV: "Multi-Topology Capability" TLV (requested code point: 0x510 from LDP registry "TLV Type Name Space"). o New Status Code: "Multi-Topology Capability not supported" (requested code point: 0x50 from LDP registry "Status Code Name Space"). o New Status Code: "Invalid Topology ID" (requested code point: 0x51 from LDP registry "Status Code Name Space"). o New Status Code: "Unknown Address Family" (requested code point: 0x52 from LDP registry "Status Code Name Space"). Registry: Range/Value E Description -------------- --- ------------------------------ 0x00000050 1 Multi-Topology Capability not supported 0x00000051 1 Invalid Topology ID 0x00000052 0 Unknown Address Family Figure 7: New Status Codes for LDP Multi Topology Extensions Zhao, et al. Expires September 12, 2012 [Page 13] Internet-Draft LDP Multi Topology Extensions March 2012 o New address families under IANA registry "Address Family Numbers": - MT IP: Multi-Topology IP version 4 (requested codepoint: 26) - MT IPv6: Multi-Topology IP version 6 (requested codepoint: 27) Figure 8: Address Family Numbers o New registry "LDP Multi-Topology (MT) ID Name Space" under "LDP Parameter" namespace. The registry is defined as: Range/Value Name ----------- ------------------------ 0 Default Topology (ISIS and OSPF) 1-4095 Unassigned 4096 ISIS IPv6 routing topology (i.e. ISIS MT ID #2) 4097-65534 Reserved (for future allocation) 65535 Wildcard Topology (ISIS or OSPF) Figure 9: LDP Multi-Topology (MT) ID Name Space 11. Acknowledgement The authors would like to thank Dan Tappan, Nabil Bitar, Huang Xin, Eric Rosen, IJsbrand Wijnands, Dimitri Papadimitriou, Yiqun Chai for their valuable comments on this draft. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers Considered Useful", BCP 82, RFC 3692, January 2004. [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. [RFC5919] Asati, R., Mohapatra, P., Chen, E., and B. Thomas, "Signaling LDP Label Advertisement Completion", RFC 5919, August 2010. [RFC5918] Asati, R., Minei, I., and B. Thomas, "Label Distribution Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class Zhao, et al. Expires September 12, 2012 [Page 14] Internet-Draft LDP Multi Topology Extensions March 2012 (FEC)", RFC 5918, August 2010. [RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas, "Label Distribution Protocol Extensions for Point-to- Multipoint and Multipoint-to-Multipoint Label Switched Paths", RFC 6388, November 2011. 12.2. Informative References [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS Networks", RFC 5920, July 2010. Appendix A. Appendix A.1. Application Scenarios A.1.1. Simplified Data-plane IGP-MT requires additional data-plane resources maintain multiple forwarding for each configured MT. On the other hand, MPLS-MT does not change the data-plane system architecture, if an IGP-MT is mapped to an MPLS-MT. In case MPLS-MT, incoming label value itself can determine an MT, and hence it requires a single NHLFE space. MPLS-MT requires only MT-RIBs in the control-plane, no need to have MT-FIBs. Forwarding IP packets over a particular MT requires either configuration or some external means at every node, to maps an attribute of incoming IP packet header to IGP-MT, which is additional overhead for network management. Whereas, MPLS-MT mapping is required only at the ingress-PE of an MPLS-MT LSP, because of each node identifies MPLS-MT LSP switching based on incoming label, hence no additional configuration is required at every node. A.1.2. Using MT for P2P Protection We know that [IP-FRR-MT] can be used for configuring alternate path via backup-mt, such that if primary link fails, then backup-MT can be used for forwarding. However, such techniques require special marking of IP packets that needs to be forwarded using backup-MT. MPLS-LDP-MT procedures simplify the forwarding of the MPLS packets over backup-MT, as MPLS-LDP-MT procedure distribute separate labels for each MT. How backup paths are computed depends on the implementation, and the algorithm. The MPLS-LDP-MT in conjunction with IGP-MT could be used to separate the primary traffic and backup traffic. For example, service providers can create a backup MT that consists of links that are meant only for backup traffic. Service providers can then establish bypass LSPs, standby LSPs, using backup MT, thus keeping undeterministic backup traffic away from the primary Zhao, et al. Expires September 12, 2012 [Page 15] Internet-Draft LDP Multi Topology Extensions March 2012 traffic. A.1.3. Using MT for mLDP Protection For the P2MP or MP2MP LSPs setup by using mLDP protocol, there is a need to setup a backup LSP to have an end to end protection for the primary LSP in the applications such as IPTV, where the end to end protection is a must. Since the mLDP LSP is setup following the IGP routes, the second LSP setup by following the IGP routes can not be guaranteed to have the link and node diversity from the primary LSP. By using MPLS-LDP-MT, two topology can be configured with complete link and node diversity, where the primary and secondary LSP can be set up independently within each topology. The two LSPs setup by this mechanism can protect each other end-to-end. A.1.4. Service Separation MPLS-MT procedures allow establishing two distinct LSPs for the same FEC, by advertising separate label mapping for each configured topology. Service providers can implement QoS using MPLS-MT procedures without requiring to create separate FEC address for each class. MPLS-MT can also be used separate multicast and unicast traffic. A.1.5. An Alternative inter-AS VPN Solution When the LSP is crossing multiple domains for the inter-as VPN scenarios, the LSP setup process can be done by configuring a set of routers which are in different domains into a new single domain with a new topology ID using the LDP multiple topology. All the routers belong this new topology will be used to carry the traffic across multiple domains and since they are in a single domain with the new topology ID, so the LDP LSP set up can be done without propagating VPN routes across AS boundaries. Authors' Addresses Quintin Zhao Huawei Technology 125 Nagog Technology Park Acton, MA 01719 US Email: quintin.zhao@huawei.com Zhao, et al. Expires September 12, 2012 [Page 16] Internet-Draft LDP Multi Topology Extensions March 2012 Luyuan Fang Cisco Systems 300 Beaver Brook Road Boxborough, MA 01719 US Email: lufang@cisco.com Chao Zhou Cisco Systems 300 Beaver Brook Road Boxborough, MA 01719 US Email: czhou@cisco.com Lianyuan Li China Mobile 53A, Xibianmennei Ave. Xunwu District, Beijing 01719 China Email: lilianyuan@chinamobile.com Ning So Verizon Business 2400 North Glenville Drive Richardson, TX 75082 USA Email: Ning.So@verizonbusiness.com Kamran Raza Cisco Systems 2000 Innovation Drive Kanata, ON K2K-3E8, MA Canada Email: E-mail: skraza@cisco.com Zhao, et al. Expires September 12, 2012 [Page 17] Internet-Draft LDP Multi Topology Extensions March 2012 Raveendra Torvi Juniper Networks 10, Technoogy Park Drive Westford, MA 01886-3140 US Email: rtorvi@juniper.net Huaimo Chen Huawei Technology 125 Nagog Technology Park Acton, MA 01719 US Email: huaimochen@huawei.com Emily Chen Huawei Technology 2330 Central Expressway Santa Clara, CA 95050 US Email: emily.chenying@huawei.com Chen Li China Mobile 53A, Xibianmennei Ave. Xunwu District, Beijing 01719 China Email: lichenyj@chinamobile.com Lu Huang China Mobile 53A, Xibianmennei Ave. Xunwu District, Beijing 01719 China Email: huanglu@chinamobile.com Daniel King Old Dog Consulting Email: E-mail: daniel@olddog.co.uk Zhao, et al. Expires September 12, 2012 [Page 18]